Noun
grass; weed; herb; thatch
月には草が生えて無い。There is no grass on the moon. ninja
Archaic
marijuana; cannabis
Slang
Prefix
not genuine; substandard
Expressions (phrases, clauses, etc.)
LOL; haha
Internet slangfrom multiple repetitions of "w" ("LOL") resembling grass: wwwwwwsee ｗ
Also written 艸【くさ】